Hot-air furnace



Patented Aug. 10, 1926.

UNITED STATES FRANK Z. AI-IL, OF SACRAMENTO, CALIFORNIA.

I HOT-AIR FURNACE.

Application filed March 2, 1925, Serial No. 12,737. Renewed Hayes, 1926.

of scale; andfor permitting of the freeout-flow of that percentage of the heat necessary to prevent condensation within the furnace, while at the same time getting all the benefits possible from the heat.

A further object is to provide a simple means for reducing to a minimum the loss of heat by radiation from the outer casing or side walls of the furnace without the use of heavy andexpensive insulation lagging on the outside.

A further object of the invention is to construct the furnace of a number of separable parts which are very easy to assemble and dismountfrom each other when necessary.

These objects I accomplish by means of such structure and relative arrangement of parts as will fully appear by a perusal of the following specification and claims.

In the drawings similar characters of reference indicate corresponding parts in the.

several views;

Fig. 1 1s a sectlonal elevation of the furnace.

7 of Fig. 1.

Fig. 3 is a perspective view of the inner heat-insulating casing member.

Fig. 4: is a similar view of the base mem ber of the main casing.

Referring now more particularly to the characters of reference on the drawings, the numeral 1 denotes a cylindrical base memberv having a rectangular orifice 2 in one side which is surrounded by a frame 3 which has an inwardly projecting flange Fig. 2 is a sectional plan on the line 22 I outer edges thereof are similarly spaced 4: all around the same. The base aiso has another opening in one side covered by screen 5. An upper casing portion 6 removably fits snugly on top of the base 1,

a circumferential bead 7 on the latter lim- I iting the downward movement of the memher 6. A cap 8 similarly fits on the member 6, the cap having a desired number ofair outlets 9 in theside thereof. These parts taken together constitute the outer shell of the furnace and are referred to as such hereinafter.

Mounted centrally in the shell and supported as hereinafter shown is the main fire chamber '10 closed at top and bottom.

In the lower end of this chamber is located I an upwardly facing gas or other suitable burner 11, the necessary air for which is obtained through a passage member 12 leading from the bottom of the chamber 10 to and extending over the flange 4. which surrounds the intake opening 2. I

Surrounding the chamber 10 and concentric therewith is a drum l3 extending to the top of said chamber but terminating short of they bottom" thereof. The inner periphery of this drum is spaced a suitable distance from the chamber to leave an air passage 14 opening from the shellbelow the chamber to the cap 8 thereabove. Air from outside the shell is admitted to this passage through the screen opening 5 which is below the drum.

The outer periphery of the drum is independently corrugated from top to bottom, as shown at 15. The bottoms of these corrugations are spaced a certain distance from the inner periphery of the drum, while the rugations and the latter are. flattened out,

as shown at 18 in Fig. 2.

This is a vital feature, since the entire.

flow of gases enters and leaves the drum through these two relatlve restricted openings and it is important that the flow shall not be choked adjacent these openings, as

otherwise the overheating of the drum or chamber at these points is apt to occur. Further wlthout these enlarged passages the heat cannot escape through the outlet fine in sufficient quantities to avoid condensatlon 1n th drum, which of course 1s an undesirable occurrence. The widened passages18 allow the free passage of the gases around thedrum from top to bottom thereof and eliminatethe above named defects.

Placing the single passage 16 opposite to the outlet 17 I insures that all gases must passaroundthe drum. before leaving the same, thus giving an even heating effectand utilizing all possible heat value in the gases.

To prevent the outer surface of the drum frombeing overheated by the action of the hot gases as they enter the drum through the passage 16, I 'mount a vertical baffle plate 16 in the drum, across the plane of the passage 16, a short distance away from the adjacent outer surface, as clearly shown in the drawings.

The fire chamber and drum arearranged as a unitary structure which is supported in the shell by transverse bars 19 mounted on 1 the base 1 on' which the bottom of the drum rests, these bars being disposed on each side of the fire chamber 10.

Depending inwardly from the base 1 ad: jacent the upper end thereof an d extending at a downward angle is an airdefiecting baffle2t) having a central opening concentric with the chamber 'andterminating just above the radial passage 12.

This causes the airentering theshell through th e side opening 5 to be deflected toward the center of'the furnace and causes the majority of the air to pass up close to both the lnner, and outer surface of the drum rather than close to theshell. The majority of the air will therefore be thoroughly heated.

To prevent any heat from the drum from being radiatedto the outer shell 61 provide an inner shell 21 open at both ends and supported by the bars 19. The shell'21. issufii ciently smaller than the shell 6 to provide an air passage therebetween, and to center in the shell 6 and projects through the shell 21 into the space between the latter and the drum so as to provide a moistening influence on the current of air being heated.

' Owing to the various parts which go to make up the furnace being detachable from each other the furnace may be easily assembled on the and as readily dismantled when necessary.

From the foregoing description it will be readily seen that I have produced such a device as substantially fulfills the objects of the invention as set forth herein.

Zhilethis specification sets forth in detail the present and preferred construction of the device, stillin practice. such deviations from such detail niay be resorted to as do not form a departure from the spirit of the invention as defined by the appended claims. i

Having thus described my invention what I claim as new and useful and" desire to secure by Letters Patent is:

1. A hot air furnace. comprising the combinationof afurnace wall providing a chamber therein a wall within thechamber providing a combustion compartment therein closed at the top and adapted to' have a source of heat at its lower end; a drum sur- 'the outer wallbeingcorrugated vertically,

means providing an outlet passage from the bott'om of the drum at one side of the combustion compartment means providing passage. communication between the, combustion compartment and the drum at the top thereof at the other side of the combustion chamher, and air inlet and exit means respectively at the bottom and top of the furnace whereby air enters the furnace-and is heated by passing upwardly about the drum and between the drumand combustion compartment and passes from thence outward through the said exit.

2. A hot air furnace compris ng the coinbination of a furnace wall providinga chambertherein a wall within the chamber pro viding a combustion compartment therein closed at theto p and adapted to have a source of heat at its lower end, a drum surrounding the" second wallin spaced relation thereto and having inner and. outer walls providing a closed chamber tlGIBbGtVVGGIl, the outer wall being corrugated vertically, a single passage between the combustion compartment and drum at the top thereof, and a single outlet passage from the drum at the bottom and at theside thereof opposite the top passage.

3. A structure as in claim 2, in which the corrugations, in the vertical plane of the 10 passages, are decreased in depth inwardly toward the inner wall, whereby to prevent restriction of the flow of combustion gases from the top passage to the outlet passage.

In testimony whereof I aflix my signature.

FRANK Z. AHL. 

